IPAC2018 - List of Authors (Chen, H.B.)

Paper	Title	Page
MOPML070	Thermal and Stress Analysis of an X-Ray Target for 6 MeV Medical Linear Accelerators	572
	Z.H. Wang, H.B. Chen, J. Shi, H. Zha TUB, Beijing, People's Republic of China
	We present an optimal design of an X-ray target for 6 MeV medical linear accelerators using FLUKA simula-tions. The target is composed of high-atomic number tungsten and high-thermal conductivity copper, corre-sponding water-cooling system is showed too. Further-more, we analyse the temperature and thermal stress re-sponses of the target under transient thermal loads using Ansys Code. For 6 MeV electron beam with 100 uA cur-rent, the results show that the target can achieve 1014 cGy/min at 1meter in front of the target. Within 100 ms, the maximum temperature reaches 512 °C under pulsed heating source with 250 Hz frequency and 1' duty cycle and the number of cycles to failure is estimated as 5.8·10⁸.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML070
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THPAL149	RF System Based on Two Klystrons and Phase Modulation for Photo-Cathode Injector	3996
	P. Wang, D.Z. Cao, H.B. Chen, J. Shi, Z.H. Wang, H. Zha TUB, Beijing, People's Republic of China
	We proposed an RF system with two klystrons, of which the powers are combined by a 3dB-hybrid. By managing the phases of the two klystrons respectively, the two pulses from the two output ports of the 3dB-hybrid can be of different powers, phases, and shapes. One of the two pulses can be set to an RF gun, while the other one can feed traveling accelerating structures. Two methods of phase modulation were proposed based on this scheme. Comparing with the state-of-art RF system, the new one can be of high efficiency or can generate electron beams with higher energy. The detailed analysis of the two methods and some experiments are described in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL149
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THPAL151	Progress in Understanding Breakdown Characteristics of X-Band Choke-Mode Structures	4002
	X.W. Wu, D.Z. Cao, H.B. Chen, J. Shi, H. Zha TUB, Beijing, People's Republic of China T. Abe, T. Higo, S. Matsumoto KEK, Ibaraki, Japan
	Funding: National Natural Science Foundation of China (Grant No. 11135004). As one of the higher-order-mode (HOM) damping structures, X-band choke-mode accelerating structures had been studied for several years. However, the breakdown characteristics of the X-band choke are still unknown. Five different single-cell choke-mode accelerating structures and one reference structure were designed, fabricated and high-gradient tested to study the related RF breakdown characteristics. The absence of field emission current flash was proposed to be the sign of breakdowns occurring inside the choke, this was verified by the post-mortem observation. Evaluation of the breakdown rate revealed that there is memory effect with pulse width and electric field. The breakdown rate in a single RF pulse did not have the 5th order pulse width and 30th order electric field dependency predicted by the empirical formula.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL151
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THPAL152	Study of X-Band Phase Shifter Using Ferrite Material	4005
	Y.L. Jiang, D.Z. Cao, H.B. Chen, J. Shi, P. Wang, H. Zha TUB, Beijing, People's Republic of China
	Ferrite has the feature of the permeability depended on the external static magnetic field, thus could be used to shift the phase of the propagating radio frequency (RF) signal. In this paper, we introduce a novel design of ferrite-based RF phase shifter. The design changes the resonant frequency of a ferrite-filled pill-box cavity to implement the phase changing. This design has a lower local RF field and a higher sensitivity on the phase changing than those of waveguide phase shifter, which may bring advantages such as higher power capacity, fast changing speed and lower insertion loss. Theory and simulation results are also presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL152
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THPAL153	High Power Test of the S-Band Spherical Pulse Compressor at Tsinghua University	4008
	P. Wang, D.Z. Cao, H.B. Chen, C. Cheng, J. Shi, Z.H. Wang, H. Zha TUB, Beijing, People's Republic of China
	We designed, fabricated and high power tested an S-band spherical pulse compressor for the high-power test facility at Tsinghua University. The pulse compressor comprises a spherical resonant cavity with an unloaded quality factor of 100, 000 and an RF polarizer with two rectangular ports and a circular port. To achieve high efficiency and large power gain, the coupling coefficient was optimized to 8 with input pulse length of 3.6 us and compression ratio of 12. After conditioning the RF system, the pulse compressor generated RF pulses with peak power of more than 400MW. And during the operation, the pulse compressor has very low breakdown rate and was extremely stable.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL153
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THPAL154	High-Gradient Performance of X-Band Choke-Mode Structures	4011
	X.W. Wu, D.Z. Cao, H.B. Chen, J. Shi, H. Zha TUB, Beijing, People's Republic of China T. Abe, T. Higo, S. Matsumoto KEK, Ibaraki, Japan
	Funding: National Natural Science Foundation of China (Grant No. 11135004) The choke-mode accelerating structure is one of the higher-order-mode (HOM) damping structures. It has the advantage of relatively simple fabrication and low surface magnetic field. C-band choke-mode accelerating structures have been successfully applied in multibunch XFEL. However, the X-band choke-mode study remains in the theoretical design stage. The high-gradient performance of the choke is still unknown. Five different single-cell choke-mode accelerating structures were designed, fabricated and high-gradient tested to study the related RF breakdown characteristics. It was observed that high electric field and small choke dimension caused serious breakdowns in the choke which was the main limitation of the high-gradient performance. The Choke-mode accelerating structures reached 130 MV/m by decreasing the electric field and increasing the choke gap. A new quantity was proposed to give the high-gradient performance limit of choke-mode accelerating structures due to RF breakdown. The new quantity was obtained from the summary of the high-gradient experiments and could be used to guide high-gradient choke-mode accelerating structure design.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL154
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THPAL155	Fabrication and Cold Test of the Correction Cavity Chain for Klystron-Based CLIC	4014
	P. Wang, D.Z. Cao, H.B. Chen, J. Shi, Z.H. Wang, H. Zha TUB, Beijing, People's Republic of China
	A proposed RF scheme based on correction cavity chain and storage cavity (CC-SC scheme) for klystron-based CLIC has the ability to generate flat output pulses. In the scheme, the correction cavity chain modulates the amplitude of the input pulse, while the storage cavity compresses the amplitude-modulated pulse. Resonant cavities of the correction cavity chain are of a relatively low unloaded quality factor and of small size, which results in the compactness of the RF scheme. The first prototype of a correction cavity chain was fabricated and cold tested at Tsinghua University and then delivered to CERN for high power test. Both the results of the cold and high power tests show that the correction cavity chain is of good performance. Feasibility and stability of the pulse compression system based on CC-SC scheme were demonstrated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL155
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THPAL156	High-Power Test of a Compact X-Band RF Rotary Joint	4017
	J. Liu, H.B. Chen, J.Q. Qiu, J. Shi, Z.H. Wang, X.W. Wu, H. Zha TUB, Beijing, People's Republic of China
	A compact X-band (9.3 GHz) RF rotary joint has been developed in the accelerator laboratory of Tsinghua University. Cold measurements on the rotary joint using Vector-Network showed good results. In recent high-power tests, the RF rotary joint was operated under a 1.6 MW X-band magnetron. The incident power, the transmitted power and the pulse width of this rotary joint have been measured. The transmitted power kept stable in different rotation angle. In this paper, the setup and results of the high-power tests of this RF rotary joint are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL156
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THPAL157	Investigation of Transverse Wakefield and Beam Break Up Effect in Irradiation Linacs	4020
	X.C. Meng, H.B. Chen, J. Shi, Z.H. Wang, H. Zha, S.X. Zheng TUB, Beijing, People's Republic of China G.H. Li, J.S. Liu, Y.H. Liu NUCTECH, Beijing, People's Republic of China
	Study of beam break up effect in linacs has been done in recent years. The beam-induced high order dipolar modes, especially the TM11-like mode were investigated for the linacs both in travelling wave and backward trav-elling wave. Measurements of beam-break up in a travel-ling wave linac were carried out and results are discussed. Moreover, a theoretical model was developed for the irradiation linacs to study the detailed interaction be-tween the transverse wakefield and the electron beam.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL157
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THPML047	Design and Measurement of the X-Band Pulse Compressor for TTX	4745
	Y.L. Jiang, H.B. Chen, C. Cheng, W. Gai, J. Shi, P. Wang, Z.H. Wang, X.W. Wu, H. Zha TUB, Beijing, People's Republic of China
	A radio frequency (RF) pulse compressor had been designed for the X-band (11.424 GHz) high power test stands at the Accelerator Laboratory of Tsinghua University. It is the SLED-I type pulse compressor, which uses a high quality factor corrugated circular cavity to store the RF power. An RF polarizer couples two quadrature modes into the cavity so that the pulse compressor needs only one cavity. The cavity implements HE1-1-14 mode, with the Q0 of 115, 000 and the coupling factor (β) of 3.23. The design and the microwave measurement before brazing of this pulse compressor are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML047
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THPML092	Electromagnetic and Mechanical Design of High Gradient S-Band Accelerator in TTX	4876
	D.Z. Cao, H.B. Chen, Y. C. Du, W. Gai, W.-H. Huang, J. Shi, C.-X. Tang, P. Wang, H. Zha TUB, Beijing, People's Republic of China
	Thomson scattering x-ray source is an essential scien-tific research tool in x-ray imaging technology for vari-ous fields. Upgrading plan of replacing the 3-meter S-band linac with a shorter structure operating at higher gradient in Tsinghua Thomson scattering X-ray source (TTX) is undergoing so far, aiming to enhance the accel-erating gradient from 15 MV/m to 30 MV/m. Detailed parameters of couplers and mechanical design of acceler-ation structure are presented in this work.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML092
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Paper

Title

Page

Thermal and Stress Analysis of an X-Ray Target for 6 MeV Medical Linear Accelerators

572

Z.H. Wang, H.B. Chen, J. Shi, H. Zha
TUB, Beijing, People's Republic of China

We present an optimal design of an X-ray target for 6 MeV medical linear accelerators using FLUKA simula-tions. The target is composed of high-atomic number tungsten and high-thermal conductivity copper, corre-sponding water-cooling system is showed too. Further-more, we analyse the temperature and thermal stress re-sponses of the target under transient thermal loads using Ansys Code. For 6 MeV electron beam with 100 uA cur-rent, the results show that the target can achieve 1014 cGy/min at 1meter in front of the target. Within 100 ms, the maximum temperature reaches 512 °C under pulsed heating source with 250 Hz frequency and 1' duty cycle and the number of cycles to failure is estimated as 5.8·10⁸.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML070

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THPAL149

RF System Based on Two Klystrons and Phase Modulation for Photo-Cathode Injector

3996

P. Wang, D.Z. Cao, H.B. Chen, J. Shi, Z.H. Wang, H. Zha
TUB, Beijing, People's Republic of China

We proposed an RF system with two klystrons, of which the powers are combined by a 3dB-hybrid. By managing the phases of the two klystrons respectively, the two pulses from the two output ports of the 3dB-hybrid can be of different powers, phases, and shapes. One of the two pulses can be set to an RF gun, while the other one can feed traveling accelerating structures. Two methods of phase modulation were proposed based on this scheme. Comparing with the state-of-art RF system, the new one can be of high efficiency or can generate electron beams with higher energy. The detailed analysis of the two methods and some experiments are described in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL149

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THPAL151

Progress in Understanding Breakdown Characteristics of X-Band Choke-Mode Structures

4002

X.W. Wu, D.Z. Cao, H.B. Chen, J. Shi, H. Zha
TUB, Beijing, People's Republic of China
T. Abe, T. Higo, S. Matsumoto
KEK, Ibaraki, Japan

Funding: National Natural Science Foundation of China (Grant No. 11135004).
As one of the higher-order-mode (HOM) damping structures, X-band choke-mode accelerating structures had been studied for several years. However, the breakdown characteristics of the X-band choke are still unknown. Five different single-cell choke-mode accelerating structures and one reference structure were designed, fabricated and high-gradient tested to study the related RF breakdown characteristics. The absence of field emission current flash was proposed to be the sign of breakdowns occurring inside the choke, this was verified by the post-mortem observation. Evaluation of the breakdown rate revealed that there is memory effect with pulse width and electric field. The breakdown rate in a single RF pulse did not have the 5th order pulse width and 30th order electric field dependency predicted by the empirical formula.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL151

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL152

Study of X-Band Phase Shifter Using Ferrite Material

4005

Y.L. Jiang, D.Z. Cao, H.B. Chen, J. Shi, P. Wang, H. Zha
TUB, Beijing, People's Republic of China

Ferrite has the feature of the permeability depended on the external static magnetic field, thus could be used to shift the phase of the propagating radio frequency (RF) signal. In this paper, we introduce a novel design of ferrite-based RF phase shifter. The design changes the resonant frequency of a ferrite-filled pill-box cavity to implement the phase changing. This design has a lower local RF field and a higher sensitivity on the phase changing than those of waveguide phase shifter, which may bring advantages such as higher power capacity, fast changing speed and lower insertion loss. Theory and simulation results are also presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL152

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL153

High Power Test of the S-Band Spherical Pulse Compressor at Tsinghua University

4008

P. Wang, D.Z. Cao, H.B. Chen, C. Cheng, J. Shi, Z.H. Wang, H. Zha
TUB, Beijing, People's Republic of China

We designed, fabricated and high power tested an S-band spherical pulse compressor for the high-power test facility at Tsinghua University. The pulse compressor comprises a spherical resonant cavity with an unloaded quality factor of 100, 000 and an RF polarizer with two rectangular ports and a circular port. To achieve high efficiency and large power gain, the coupling coefficient was optimized to 8 with input pulse length of 3.6 us and compression ratio of 12. After conditioning the RF system, the pulse compressor generated RF pulses with peak power of more than 400MW. And during the operation, the pulse compressor has very low breakdown rate and was extremely stable.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL153

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL154

High-Gradient Performance of X-Band Choke-Mode Structures

4011

X.W. Wu, D.Z. Cao, H.B. Chen, J. Shi, H. Zha
TUB, Beijing, People's Republic of China
T. Abe, T. Higo, S. Matsumoto
KEK, Ibaraki, Japan

Funding: National Natural Science Foundation of China (Grant No. 11135004)
The choke-mode accelerating structure is one of the higher-order-mode (HOM) damping structures. It has the advantage of relatively simple fabrication and low surface magnetic field. C-band choke-mode accelerating structures have been successfully applied in multibunch XFEL. However, the X-band choke-mode study remains in the theoretical design stage. The high-gradient performance of the choke is still unknown. Five different single-cell choke-mode accelerating structures were designed, fabricated and high-gradient tested to study the related RF breakdown characteristics. It was observed that high electric field and small choke dimension caused serious breakdowns in the choke which was the main limitation of the high-gradient performance. The Choke-mode accelerating structures reached 130 MV/m by decreasing the electric field and increasing the choke gap. A new quantity was proposed to give the high-gradient performance limit of choke-mode accelerating structures due to RF breakdown. The new quantity was obtained from the summary of the high-gradient experiments and could be used to guide high-gradient choke-mode accelerating structure design.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL154

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL155

Fabrication and Cold Test of the Correction Cavity Chain for Klystron-Based CLIC

4014

P. Wang, D.Z. Cao, H.B. Chen, J. Shi, Z.H. Wang, H. Zha
TUB, Beijing, People's Republic of China

A proposed RF scheme based on correction cavity chain and storage cavity (CC-SC scheme) for klystron-based CLIC has the ability to generate flat output pulses. In the scheme, the correction cavity chain modulates the amplitude of the input pulse, while the storage cavity compresses the amplitude-modulated pulse. Resonant cavities of the correction cavity chain are of a relatively low unloaded quality factor and of small size, which results in the compactness of the RF scheme. The first prototype of a correction cavity chain was fabricated and cold tested at Tsinghua University and then delivered to CERN for high power test. Both the results of the cold and high power tests show that the correction cavity chain is of good performance. Feasibility and stability of the pulse compression system based on CC-SC scheme were demonstrated.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL155

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL156

High-Power Test of a Compact X-Band RF Rotary Joint

4017

J. Liu, H.B. Chen, J.Q. Qiu, J. Shi, Z.H. Wang, X.W. Wu, H. Zha
TUB, Beijing, People's Republic of China

A compact X-band (9.3 GHz) RF rotary joint has been developed in the accelerator laboratory of Tsinghua University. Cold measurements on the rotary joint using Vector-Network showed good results. In recent high-power tests, the RF rotary joint was operated under a 1.6 MW X-band magnetron. The incident power, the transmitted power and the pulse width of this rotary joint have been measured. The transmitted power kept stable in different rotation angle. In this paper, the setup and results of the high-power tests of this RF rotary joint are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL156

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL157

Investigation of Transverse Wakefield and Beam Break Up Effect in Irradiation Linacs

4020

X.C. Meng, H.B. Chen, J. Shi, Z.H. Wang, H. Zha, S.X. Zheng
TUB, Beijing, People's Republic of China
G.H. Li, J.S. Liu, Y.H. Liu
NUCTECH, Beijing, People's Republic of China

Study of beam break up effect in linacs has been done in recent years. The beam-induced high order dipolar modes, especially the TM11-like mode were investigated for the linacs both in travelling wave and backward trav-elling wave. Measurements of beam-break up in a travel-ling wave linac were carried out and results are discussed. Moreover, a theoretical model was developed for the irradiation linacs to study the detailed interaction be-tween the transverse wakefield and the electron beam.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL157

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML047

Design and Measurement of the X-Band Pulse Compressor for TTX

4745

Y.L. Jiang, H.B. Chen, C. Cheng, W. Gai, J. Shi, P. Wang, Z.H. Wang, X.W. Wu, H. Zha
TUB, Beijing, People's Republic of China

A radio frequency (RF) pulse compressor had been designed for the X-band (11.424 GHz) high power test stands at the Accelerator Laboratory of Tsinghua University. It is the SLED-I type pulse compressor, which uses a high quality factor corrugated circular cavity to store the RF power. An RF polarizer couples two quadrature modes into the cavity so that the pulse compressor needs only one cavity. The cavity implements HE1-1-14 mode, with the Q0 of 115, 000 and the coupling factor (β) of 3.23. The design and the microwave measurement before brazing of this pulse compressor are presented in this paper.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML047

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPML092

Electromagnetic and Mechanical Design of High Gradient S-Band Accelerator in TTX

4876

D.Z. Cao, H.B. Chen, Y. C. Du, W. Gai, W.-H. Huang, J. Shi, C.-X. Tang, P. Wang, H. Zha
TUB, Beijing, People's Republic of China

Thomson scattering x-ray source is an essential scien-tific research tool in x-ray imaging technology for vari-ous fields. Upgrading plan of replacing the 3-meter S-band linac with a shorter structure operating at higher gradient in Tsinghua Thomson scattering X-ray source (TTX) is undergoing so far, aiming to enhance the accel-erating gradient from 15 MV/m to 30 MV/m. Detailed parameters of couplers and mechanical design of acceler-ation structure are presented in this work.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML092

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)